Why should you care?

ShopNest payment provider blips should not fail checkout on the first timeout.

See it live — copy this example

Paste into a C# console or class library project and run dotnet run.

public static async Task<T> RetryAsync<T>(Func<Task<T>> action, int attempts = 3)
{
    for (var i = 1; i <= attempts; i++)
    {
        try { return await action(); }
        catch when (i < attempts)
        {
            await Task.Delay(TimeSpan.FromMilliseconds(100 * i));
        }
    }
    return await action();
}

var result = await RetryAsync(async () =>
{
    Console.WriteLine("call psp");
    return "ok";
});
Console.WriteLine(result);

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• Backoff reduces stampedes.
• Only retry transient errors.
• Idempotency keys required for payments.
• Polly is the usual library (later lesson).

Practice next

1. Run the helper.
2. Throw on first call and succeed on second.
3. Do not retry on validation errors.
4. Cap attempts at 5.
5. Log each attempt number.

Remember

Retry transient faults. Backoff + jitter. Idempotent operations.

ShopNest PSP retries

Capture retries twice with backoff + idempotency key.

Outcome: Blips recover; doubles do not charge twice.